Luer fittings for Luer locks employ male and female tapered mating surfaces for a releasably secure connection between, for example, two portions of a conduit. For example, in the medical field, many intravenous fluid solution sets have at one end a tapered male Luer fitting for connection with a female Luer fitting disposed in the hub of a catheter disposed in a patient. Such male Luer fittings are used, for example, on most solution administration sets sold by Travenol Laboratories, Inc., of Deerfield, Ill.
To increase the strength of the connection between the Luer fittings, male Luer fittings often include a locking ring mounted coaxially about the male Luer fitting. The locking ring typically includes internal threads which engage flanges extending from the outside of the female Luer fitting. While the locking ring is often integral with and stationary with respect to the male Luer fitting, other locking rings are slidable relative to the fitting. An example of a Luer fitting having a locking ring which is slidable on the fitting is seen on administration set Product Code No. 2C1200, sold by Travenol Laboratories, Inc. Such a male Luer fitting having a slidable locking ring is also shown in United Kingdom Patent Application No. 8015291, Publication No. 2055166, filed May 8, 1980. A female Luer fitting is shown in that publication, as well as on the hub of a QUIK-CATH.RTM. Catheter, Product Code No. 2N1106, sold by Travenol Laboratories, Inc.
The use of a male Luer fitting having a locking ring with a female Luer fitting having extending flanges typically does increase the security of the connection. The locking ring and flanges prevent the two Luer fittings from inadvertently separating.
The assignee of the present invention is engaged in developing disposable infusion devices for infusing quantities of medical fluid. Such an infusion device has been assigned Product Code No. 2C9056 by Travenol Laboratories, Inc., a subsidiary of the assignee of the present invention. Such a device is shown generally in U.S. Pat. No. 4,318,400 to Peery, et al. As seen in that patent, a supply of liquid to be infused into a patient is stored under pressure. Typically, such infusion devices are used by hospital pharmacists, who fill the infusors with prescribed medical fluids. The hospital pharmacist then gives the infusor to a patient who is usually ambulatory and frequently an out-patient. Thus, there is an extended period of time of, for example, up to two weeks between the time of infusor filling by the pharmacist and use by a patient.
The infusion device includes a male Luer fitting at its outlet for connection by the patient to, for example, a catheter hub. The contents of the pressurized infusor are in open communication with the male Luer fitting. Up until the development of the sealing closure of the present invention, it has been difficult to provide a female Luer-type closure for the male Luer fitting which prevents liquid leakage from the infusor reservoir. It has been found that the interlocking Luer fitments described above employing the locking ring/flange combination, while secure, are incapable of preventing liquid leakage over time from a pressurized supply. It is believed that liquid leakage occurs primarly due to cold flow or creep between the male Luer fitting on the infusor and the female Luer-type closure.